Under cold start conditions, most gasoline and diesel vehicles emit hydrocarbon, carbon monoxide, and nitrogen oxide (NOx) emissions before the exhaust catalyst has achieved light-off temperature (e.g., before it is fully functioning). Increases in engine efficiency and increased use of turbocharging may exacerbate this problem because less exhaust gas heat may be available to the three-way catalyst (TWC), thereby increasing the time it takes the catalyst to reach a light-off temperature. A TWC is typically comprised of a washcoat loaded onto a support material, such as a cordierite substrate. Both the substrate and the washcoat contribute to the total thermal mass of the catalyst. Reducing substrate thermal mass has been utilized as a method to reduce the heat capacity of the catalyst, potentially resulting in faster catalyst light-off.